He's such a pleasure to keep. And a very active betta! I've had bettas that just sit at the surface, but he keeps swimming. just keep swimming, just keep swimming... lol.
As I understand it, most metallics were created through crosses with smaragdina or imbellis, since they're much more widely available. You could be right, though.
The double-striped gill plate was what clued me in, a Mahachai-specific trait, and that his body is a little longer than your standard B. splendens. I wonder if he'll throw any plakats as a result?